What is a kidney capacitor?
A condenser microphone like the AT2020 contains a very sensitive diaphragm that captures the vibrations of the sounds you want to record. This diaphragm is so sensitive that it needs to be powered via the XLR cable* to ensure that every nuance of your instrument or voice is captured crystal clear and detailed.
Audio-Technica microphones with cardioid pattern have a heart thanks to the shape of the sound detection surface - in the transmitted and literal sense. Microphones with cardioid pattern take what is in front of them in a coarse heart shape, from the tip of the sound detection at the front of the microphone to the graduated detection to the sides. This cardioid pattern improves the isolation of any desired sound source for rich and precise recordings.
*XLR cable sold separately.